Hey folks-
With the visible increase in interest of 9mm and other pistol caliber AR's, I've put together some of the things I've learned from the rest of the members...hope this helps shed some light on this segment of AR's. I'll add what I have today...Feedback is appreciated. Regards, squibload

Q: Who should I buy a 9mm AR rifle from?

A: This is not the right first question. The first question that you need to answer is "Which 'style' rifle should I buy?" In this case, "Style" refers mainly to the types of magazines used in the design. They are generally designated as "Colt" style and "Olympic" (aka "OLY") style. The manufacturers of each design are mentioned below.

Q: O.K., which "style" 9mm AR should I buy?

A: There are pros and cons to each style rifle, and most shooters make the decision based on the cost of the rifleâ€™s magazines. The "Colt" system uses simple stick magazines. Prices can range from $20 each for aftermarket mags to $40-50 and up for new, authentic Colt 32 round mags.

There are a wide variety of different magazine blocks that hold the Colt's magazines in place. Original Colt lowers had aluminum blocks roll-pinned in place (fore-and aft). Aftermarket blocks that drop in front the top of the lower ("top-loading") and others that are held in place via set-screws are available. Whatever the style of block, the Colt system uses magazines of the same dimensions, and the magazines use the standard magazine catch. You can also use Uzi magazines that have been modded to fit the Colt mag blocks.

The "OLY" system is a bit more unique...Olympic Arms has shipped four different magazine types in their history.

1. Back in the day, they shipped their conversion uppers with a standard Sten magazine and a magazine well block.
PRO: Cheap magazines. A huge load of Sten mags were in-country during the 1994 Assault Weapons ban, and these were among the few types of magazines that were still actually affordable during the ban. This caused a jump in popularity for the OLY Style.
CON: Reloads require a different manual of arms...since only the magazine block is retained by the mag catch, the magazine was held in place by a lever (think AK-47). So, if you hit the mag catch button, you dump both the magazine AND the mag block. And if you ever try to load a 32 round Sten Magazine by hand, you'll probably get sore thumbs by about round 15.

2. They switched to a modified Sten magazine (with a piece of square steel welded on the back...the steel block had a machined notch in it, to fit up with the standard AR magazine catch).
PRO: Same manual of arms as every other AR15 out there.
CON: These mags were expensive, and don't fit well in most magazine carriers. Since these are still Sten magazines at heart, they're a PITA to load without a loader.

3. As of 2011, Olympic Arms is shipping their standard conversion kits with a proprietary polymer magazine. It fills the entire magwell, and is shaped like a GI 30-round 5.56 magazine.
PRO: Seemingly good reviews for reliability.
CON: Expensive, when compared to surplus Sten mags. Polymer, with a huge "OLYMPIC ARMS" logo on the side. Only available from Olympic, or used.

4. Olympic also sells a Glock-based conversion kit.
PRO: Owner can have a handgun/longgun combination that use the same magazine.
CON: The conversion is ugly as hell. But, you're using the very reliable Glock magazine...

Though the magazines are the primary differentiator, there are other differences that you should be aware of.

In short: If you want to use a standard AR15 lower receiver, with no modifications whatsoever, the OLY style will work immediately. If you have one, single lower receiver, and you want to swap a conversion kit with your standard 5.56 or other upper, this is a good way to go.

If you have a dedicated lower receiver for your pistol-cal rifle (and why not...they're cheap!) the Colt style is probably a better option. However, to make your Colt style run well, you'll need specific parts. A unique hammer, a ramped bolt carrier, heavy buffer, etc. will be valuable in making your Colt-style 9mm AR rifle run smoothly.

Ive looked into buying a Colt 9mm but the prob I run into in NJ is that they are LEO only...
I dont think I can get one unless you have an idea how I can legally.
I like the colt because its the one I had been shooting at the indoor range here but they wont sell me one and I am told it is not NJ legal
any input here???
what shoud I do

Originally Posted By 555R:
Ive looked into buying a Colt 9mm but the prob I run into in NJ is that they are LEO only...
I dont think I can get one unless you have an idea how I can legally.
I like the colt because its the one I had been shooting at the indoor range here but they wont sell me one and I am told it is not NJ legal
any input here???
what shoud I do

Squibload-
I have an Oly 9mm upper and would like to get a block to allow me to use my extra sten mags. Do you know where I can get one compatible with the Oly system? When I spoke to them on the phone, they told me they carry no block anymore. Thanks for the information.

i've recently purchased a oly 9mm upper and socom mag block.they work excellent!used sten mags or new ones from cdnn.mounted a cheap red dot and its a gas. been shotting it at ipsc stages after our match. buying new sten 32rd mags for only 5 bucks sure makes this carbine sweet.

I am continuosly adding info based on various member questions. I personally have a Rock River Arms 9mm upper, and can answer questions on those with authority. I also know plenty about the Olympic Arms system, although I do not have one in my hands.

If you find any incorrect information please let me know and I will update the FAQ.

Q: "What is the cheapest, easiest way I can get into a 9mm system with my current 5.56mm AR?"

A: There are two "cheap and easy" ways to get into a 9mm AR setup, both which will cost around $600 or so:

Olympic Arms 9mm upper. It comes with a modified Sten magazine that has a block welded to the back and works with the standard magazine catch, allowing you to simply slap on the upper, stick the mag in the magwell and rock and roll. However, this style of magazine is expensive ($60) and won't fit in a standard 9mm mag pouch. Most people get a SOCOM Manufacturing magazine bolc, which is held in by the standard magazine catch and works kind of like an AK or HK paddel catch. It allows you to use standard, unmodified Sten mags. Here is the price breakdown:

Olympic Arms 9mm upper: $550 (from Atlantic Firearms or Triple Break Products)SOCOM Mfg mag block: $70 shipped (from SOCOM Manufacturing)Sten mags (32 round cap) $3.99 each from TAPCOTotal cost with 5 mags: $640*note: Upper comes with one modified Sten mag- you can probably sell it and get $50 for it on the EE if you have no need for it

Colt/Rock River arms 9mm upperThe other directioni to go is the "Colt Style" system. I say this in parenthesis as most people actually buy a Rock River Arms upper, as they are half the price of colt and are exaclty the same. I personally have one of these and they work great. The cheapest way to go with these is Rock River Arms 9mm upper, a VM Hyetch magazine block, and Uzi mags. The VM Hytech block is cool as it is inserted up into the magwell and held by the standard mag catch, and ha its own mag catch that works with the standard Uzi magazine. Here is the price breakdown:

Other thoughts:Although the Rock River Arms setup appears to be slightly cheaper, you can easily recoup some money by selling the modified Sten mag that comes with the Olympic Arms upper. If you are using the SOCOM block there is really no need for it.

Also, about 25-30% of the time the Rock River Arms setup requires a little "Tweaking" to get it running properly. the most common problem is that it will not strip the last 1-4 rounds out of the Uzi mag, the reason being that the Uzi follower has too steep and angle for the bolt to strip the rounds. This is easy to fix with about two minutes a mag and a pair of pliers (just did it myself) and the mags will still work in an Uzi, but some people don't like having to "tweak" their weapon to get it to run. Also, you might have to get another hammer- the DMPS style AR15 hammer (looks basically like an M16 hammer with the back "rat tail" choped off) works for both .223 and 9mm. Many AR-15's are equipped with a hammer that has a small face out of the top front, and that can hang up on the bolt carrier and cause a bad jam. Figure $15 for a new hammer from Brownells. One final thing that many people do is have the bolt "ramped" as the 9mm bolt can beat kinda hard on the hammer and pins. It is not necessary on a semi lower, the full autos are the ones that seem to get beat pretty hard as they fire so many rounds, but I perosnally figure "it can't hurt." LRM firearms does this service for $35.

So as you can see, you will be looking at an investment of around $600 either way. The ultra plug-and-play system seems to be the Olympic upper, although the Rock River Arms is really nice if you already have an Uzi and Uzi mags (like I do).

Q: "What types of magzine blocks are available, I hear all sorts of names. Which blocks work with Which system? Which require modified magazines?"

A: "Here you go, broken down by whch system uses them."

Colt pattern mag blocks

Colt Mag Block-Usually pinned into a Colt lower, but can sometimes be found on the Equipment Exchange-Bottom loader-Uses setscrew (and pinnning in many instances) to secure-Has bolt hold-open feature

"Old" Rock River Arms mag blockCopy of Colt Mag Block above

"New" Rock River Arms mag block-Bottom Loader-Uses set screw to secure-No bolt hold-open feature-Replaced "Old" Rock River Mag block around January 2005. Several RRA vendors have told people it is not worth the money ($150).

American Spirit Arms Block-Top Loader model -No bolt hold-open feature*Note- apparently there are two versions, one designed for ribbed-back Uzi mags and one that is designed for the plasma tube welded Uzi mags with no back rib.

The CrossFire 9mm magwell conversion block is ALL steel and it is placed into the magwell through the bottom upwards. A ball detent on the front of the block has tension that holds it into place in the magwell. It also has an area on the side of the block where the magazine release fits into and holds it into place. When you release the magazine release button, it allows the magazine to drop free but still holds the block into place. The feed ramp allows just about any size of 9mm to be used and it is a part of the block. Is the feed ramp welded or machined to the block itself, I'm not sure since I don't have the block in front of me to look at. I've never had a round jam or FTF due to the the feed ramp. The ejector is held in the block by a pin I believe, so it can be replaced if need be. My ejector rides "nearly" side by side with my bolt without actually touching the bolt, and this has given me NEAR flawless performance at ejecting cases. This is critical and on some setups may need to be tweaked. One of the best features on the CrossFire is holding the bolt open on the last round fired WHEN using Colt mags. It really improves your ability to perform better at subgun shoots with this feature. The only problems I've ever really had was due to bad or damaged ammo but that is no fault of the CrossFire block. I hope this helps

Olympic Arms modified magazines--magazines have a block welded to them and no adapter is requred. Have a funky "L" shape look to them.-Were also manufactured by Dalphon, which went out of business Jan. 2004.

Lowers not requiring adapters

Cavalry Arms lower-prototype "MKII" lower has a cruciform look to magwell cutout. Magwell is wide enough in middle to accomodate a Thompson magazine. -Rumor has it several companies are looking at designing .45 ACP uppers to use this lower, but none available as of March 2004.

www.m60joe.comMagazine notching to make Uzi mags work in various mag blocks, bolt ramping, etc.

www.uzitalk.comGood FAQ on the different types of Uzi mags available and their relative merits and weaknesses

www.coledistributing.comCheapest source of Uzi mags I have found- $99 for 10 used 25 round IMI mags, $1 ea for handpick. Got mine back in Dec 2003, rumor has it they are out right now. That special was not listed on their website, you have to call.

www.cdnninvestments.comAnother excellent source of Uzi mags, but website is not always up to date. Call for specials.

Data on 9mm Colt style systems

Colt/RRA bolts come in "full auto" config, although a very few "semi" style colt bolts were made. Both work fine for semi.

An unmodified bolt can use either a 9mm style hammer, an M16 hammer with the back end cut off (so as not to be illegal per NFA), or a DPMS style 5.56 hammer (which does not have the small rectangular notch on the front top face). The standard 5.56 AR-15 hammer with the small notch on the fron top face will bind the bolt *badly* on the first shot!

The DPMS/M16 (modified) hammer may suffer trigger slap with a 9mm upper, but will function.

A 5.56 upper will not function with a 9mm hammer in the lower

A ramped bolt will work with all AR-15 and M16 hammers (modify M16 hammer to be NFA compliant!). It may not function with a 9mm hammer, results have varied and seem to depend on tolerances between bolt/upper/lower.

Hollow point rounds may not feed reliably initially and mag blocks may need to be "throated" to help the feeding.

Ramping a Colt style 9mm Bolt: Why??

Although a Colt/Rock River 9mm upper will work with most hammers, it really was intended to be used with the Rock River 9mm hammer. The hammers are reset in only 1/2" of bolt travel, which puts a considerable stress on both the hammer and the hammer pins. Although it will not ruin a gun immediately, on a long enough time scale, espeically on full auto guns, this constant beating can wear on the lower and in some instances will "egg out" the hammer in holes. The easy solution to this is to "ramp" the bolt, where the ramped area is increased in length (a shallower slope) thus increasing the reset distance to about 1 1/4" or so, and more than doubling the reset time of the hammer, thus lowering the impact forces on the lower, pins, etc.

The following picture shows an unramped bolt carrier on top and a ramped bolt carrierat the bottom. Note that the top bolt is actaully an M16 cariier, but the unramped porition is identical to that of an unramped 9mm bolt. The ramped area is just under the firing pin and is the shiny/scratched area on the lower bolt carrier in the picture. Note that most times when this area is ramped it is left "in the white" and not reparkerized. See the ahmmer picture at the bottom of this post to better understand what has been "ramped" on the bolt:

Muzzle Threading:

Muzzle is threaded 1/2x36 threads per inch on 9mm barrels (at RRA/Colt factory) as opposed to the 1/2x28 tpi use on 5.56

Olympic will thread 9mm only in 5/8x24 by default or 1/2x28 when asked. Other pistol caliber barrels are threaded 5/8x24. (Per Mark Budam at Triple Break Products)

1. M16 hammer. Description: It has a "hook" on the back edge which allows for full auto with the proper parts. WARNING: These are Illegal to posses in their orignal form per NFA unless installed in a registered class III weapon!Works in: M16: YesAR-15: Yes, but only with spur removedColt Style 9mm: Yes, but only with spur removedColt Style 9mm w/Ramped Bolt: YesOlympic Arms Pistol upper: Yes, but only with spur removed

4. AR-15 ("Rock River") Style hammerDescription: Similar to M16 hammer but with no spur/hook on back and a notch at the top front faceM16: Yes(?)AR-15: YesColt Style 9mm: No. WARNING- this will most likely BADLY jam hammer against bolt on first shot and not only jam weapon, but make removal of upper from lower extremely difficult!Colt Style 9mm w/Ramped Bolt: YesOlympic Arms Pistol upper: Yes

The following picture shows from left toe right an M-16 hammer with the "rat tail" removed, a "DPMS" style AR-15 hammer (also referred to as a "Sporter Hammer" by some people" and a "Rock River" style AR-15 hammer on the right, which is the most common type of AR-15 hammer. A 9mm bolt/carrier (is shown above, and note the ramping on the underside- the gradual slope of whcih can easily be seen.

...God gave us two shoulders one for the AR and one for the AK
And a round hip for...the good ol' 1911
Shadow_Warrior, 12/07/03

OK, how about another question for the experts...
Can a person mix and match Bolt/Carrier units for the Colt Style 9mm uppers, ie will a RRA or ASA Bolt/Carrier unit work in a Colt Upper (or the opposites)?
Are all of the various Mag blocks for the Colt style uppers interchangeable?
Will a standard 5.56 buffer/spring work with a 9mm?

Originally Posted By Quarterbore:Can a person mix and match Bolt unit for the Colt Style 9mm uppers, ie will a RRA or ASA Bolt unit work in a Colt Upper (or the opposites)?

All are Colt pattern, no difference, unless one fella decided to deviate from std pattern. I am using a Garrison Mfg bolt, Kent said it was made to "Colt" specs, he is only 2hr away, so I bought from him, my barrel was cut from blank, to Colt pattern.

Are all of the various Mag blocks for the Colt style uppers interchangeable?

All were made to Use std Colt mags in std Colt location. Only real difference is most now are 1 piece, and some will operate the bolt hold if Colt mags used. 1 or 2 other drop in from top. I borrewed an ASA drop-in top block from fella that uses it in his SP-1 M16, worked fine in my OLY lower with barrel from blank, Garrison bolt, and notched Uzi mag.

Will a standard 5.56 buffer/spring work with a 9mm?

I fired the mix of parts in mine using a std A2 hard stock, A2 buffer and plain recoil spring, no problem here.

What is different between an AR-15 5.56 fire control group (hammer) and the hammer of the 9mm?

Note: I know it has to do with the profile and I know many people just dremmel the auto sear catch on an M-16 hammer but I do not understand the specifics on why this is necessary. Following is a pic of the M-16 and AR-15 hammer...

Also, does anybody know if a 9mm Colt Upper will work with a Jewell 2-stage trigger?

What is different between an AR-15 5.56 fire control group (hammer) and the hammer of the 9mm?

Note: I know it has to do with the profile and I know many people just dremmel the auto sear catch on an M-16 hammer but I do not understand the specifics on why this is necessary. Following is a pic of the M-16 and AR-15 hammer...

Also, does anybody know if a 9mm Colt Upper will work with a Jewell 2-stage trigger?

Ken, the std AR hammers' notch/barb there on the face will catch in the groove (see red circle) on the std Colt pattern 9mm bolt and lock up the works with the bolt partially open when you attempt to close the bolt. Makes for a bitch to un-F&%# the mess. SOOO, Colt made a hammer (semi) that is missing most of the body (refer to 9mm hammer pic at biggerhammer).

The Bolt with the blue stripe shows the "ramp" that is cut to mimmick the std AR-M16 carriers ramp.... With this, you can use your plain old AR notched face hammer, or any other AR trigger system, and forget about the special 9mm hammer. (photo courtesy of joeblack)

]

M16-9mm (FA)uses std M16 hammer, or in an AR (semi) you can cut the auto lug off. Some people have stated that this hammer system with the red circled bolt will transfer some energy back into the hammer-pin, causing the hammer pin to break/egg the hole in the lower over time, or trigger bite. Have not noticed any slap with my SBR.

STUPID ME took the photo properties from the fresh upload (jpeg,orig.jpeg), rather than let the pic float into storage bin, where i copied it, and repaired the link.

So, does any of the various Colt style 9mm Bolt/Carrier assemblies come with the proper ramp to allow traditional trigger groups to be used (Colt, RRA, ASA)?

Not that I am aware of yet.... I have a Garrison Mfg bolt, Kent said it is Colt spec, so I bought it, looks like the one in the pic with the red circle.------(photo courtesy of Joeblack, I painted),, Floating around somewhere joeblack posted a pic of a bolt somebody sent him, appeared to be a partial ramp cut (I do not know if source of bolt is known, but Robert/amphibian speculated may be new style Colt), and had another bolt that did not have a notch on it as seen in the pic with red circle.

I seen a semi Colt factory 9mm not long ago, had the same 9mm bolt (rare semi bolt), and had the 9mm semi hammer. Full auto uses regular M16 parts.

After last post, wife said I had to see flooding (5 days of storms here).
Anyway, the pic you have is of course the std AR/M16 bolt-carrier assembly. The 9mm uses a 1 piece bolt assembly, as it is "blow-back" - See pics. The front has a .125" recess for case to sit with extractor and fire pin. You see the head of the fire pin in the middle of the bolt.
The other pic is the business end of the bolt, though foggy, I need to get a better pic, sorry for poor pic on this one. The thumbnail pic looks good though......
[img]http://www.imagestation.com/picture/sraid69/p50474a24a228a51f600b3da61f2d79b5/fbb78601.jpg[/img]
[img]http://www.imagestation.com/picture/sraid69/p5dad120b1b6c738015cf0ea4573da28a/fbb785ff.jpg[/img]
[img]http://www.imagestation.com/picture/sraid69/p5dad120b1b6c738015cf0ea4573da28a/fbb785ff.jpg.thumb.jpg[/img]
[b]EDIT[/b] I borrowed a pic from SAWLESALES:
[img]http://www.sawlesales.com/images/schematic5.gif[/img]

I looked at my Jewell and it does have the same funky notch in the front side of the hammer. I would like to keep my 2-stage trigger in my lower if I can so I guess I need to look for an M-16 style 9mm carrier, plan on modifying a semi 9mm carrier to work, or perhaps modify the jewell 2-stage trigger group's hammer.

Thanks for helping a understand the 9mm system!

FWIW: I have a Colt 9mm Upper that I just bought with the JRW 2-pc block and a few modified UZI mags. I just do not have the bolt/carrier group so I can actually use it.

Just call/e-mail Kent at Garrison Mfg. He is just north of me outside Toledo. He can usually get one right out, and his price is the the least of all the makers @ $149.95 (ASA/RRA/Colt). I e-mailed him, and he called me that evening and took my order.

You will not find a Semi 9mm bolt, it is a Colt oddity, std is M16 style bolt (like in the pics).

Get ahold of joeblack, and have Kent ship there first (joe is somewhere near the Medina/Akron/Canton area), and let joe cut the ramp, then you'll be all set to run any trigger-hammer combo you wish.

I am still waiting for my RRA 9mm upper so I have a lot of time to read post from you guys out there, which has been a great help, but I do have one question. Which mag block is better the ASA drop in version or the RRA. I've read one message that suggested the ASA, but I wanted to find out the favored model from several of the experts out there.
If the Sten mag blocks ever make it into production I'll have to get one, but there hasn't been any talk of that lately.
Thanks for you input.